Virtual Fitting Rooms

Photonics.comAug 2008
MUNCHEN, Germany, Aug. 26, 2008 – Fitting rooms may soon become a thing of the past. Scientists at the Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institute HHI, have developed what they have dubbed the “virtual mirror.”

This mirror-like display enables shoppers to see themselves wearing different items of clothing without actually having to try them on.

On display at the IFA consumer electronics show in Berlin from Aug. 29 to Sept.3, this technology has been likened to a magic mirror because of its ability to show the consumer wearing a range of different designs without having to take one off to try another.

“The principle is similar to the virtual shoe-fitting mirror that we developed last year for the Adidas flagship store in Paris,” says Anna Hilsmann of the HHI. “But it is somewhat more difficult to create a realistic impression of T-shirts, shirts or sweaters in a virtual mirror. These items of clothing develop folds that partially distort the image depending how the wearer moves about.”

Because textiles have elastic qualities, their structure is not always uniform, and there are innumerable details that give each material its special appeal. These characteristics represent a challenge for the virtual mirror.

“To reproduce elastic deformations such as those in a woven or knitted fabric, we have to evaluate many different parameters and process them all simultaneously,” said Hilsmann.

As an interactive part of the show in Berlin, the team of researchers has decided to demonstrate their technology by allowing visitors to see how easy it is to display different logos or graphics on the same t-shirt.

So what does a stress-free fitting room look like? The customer stands in front of a display that has a camera mounted above it. By filming the person, the camera registers the way their clothing flows and moves. To change clothes, the logo on a T-shirt might be replaced with a different, virtual design, for example. The wearer then sees their own image in the display wearing the same T-shirt but with a blue Fraunhofer logo in place of the original green one.

To make the image in the magic mirror appear as realistic as possible, the folds and creases in the clothes actually worn by the user are reproduced in the virtual representation, even when the user is moving about. The shadows and lighting effects seen in the virtual mirror are also identical to those on the real person.

According to Hilsmann, the ingenious part consists in “calculating the spatial parameters of the projected image on the basis of a two-dimensional model. This reduces the number of dimensions we need to simulate the image and allows us to rapidly evaluate any movements.”

The 2-D model consists of a closely meshed network of triangular fields. This is sufficient to predict any changes. The system also knows the direction in which the fabric is capable of stretching or flowing – in other words its specific deformation behavior. To allow the virtual image to reflect these changes as realistically as possible, the apexes of the triangles can be displaced independently of one another.

The camera shoots frames at intervals of a few milliseconds and transmits them to a memory unit. Here, the images are analyzed to determine what changes have taken place between successive frames. To do so, a triangular meshwork is superimposed on each frame, employing a technique commonly used in computer graphics. Since the content of the triangular fields doesn’t necessarily change from one frame to the next, the system only compares those fields where changes have actually taken place.

This information is used to create a new virtual image of the item of clothing, incorporating the new logo. The images are processed in real time. Consequently, users have the impression that the image reflected in the display follows every movement they make, including the way this affects the folds and creases in the clothes they are wearing, just like a real mirror. A touch screen allows shoppers to choose different styles and colors of the garment they have selected, helping them to decide which color or design suits them best.

“Shoes and clothes are just the first stage,” added Hilsmann. “The virtual mirror could also be used to help customers select eyewear or jewelry.”

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